As wind turbines tend to provide more power, the weight and dimensions of their components increase considerably and, consequently, the towers become taller and more robust. As a result, the transport of the towers must be divided into parts, and some parts even into sections, making the assembly of a wind turbine ever more complicated and costly. One way of reducing the high costs of the wind turbine assembly process consists in the substitution of large sized cranes for conventional cranes and for assembly devices. Below is a state of the art summary relating to the inventions used for the assembly of towers and wind turbines.
Patent application U.S. Pat. No. 6,782,667 proposes a wind turbine assembly system based on a telescopic tower which is erected using a pivoting structure. Once the tower is placed in a vertical position, its parts are deployed using a series of cables and pulleys located inside the tower.
Patent application U.S. 20050005562 also describes a telescopic tower with pulleys which elevate or collect the different parts of the wind turbine tower. In this sense, there are a large number of patents related to telescopic towers which are erected via the use of pulleys and cables located within the structure, such as patent applications U.S. Pat. Nos. 3,248,831, 4,785,309, CH677516, EP0942119, etc.
Patent application DE19647515 avoids the use of large infrastructures for the installation of towers, using a mechanism to elevate and assemble the parts of the tower which is fixed to and advances along the exterior of the parts of the tower already installed.
Patent application U.S. Pat. No. 6,955,025 describes an assembly method based on the use of telescopic cranes of large dimensions sufficient for lifting a wind turbine that has articulated tower parts.
Patent application U.S. Pat. No. 4,590,718 describes a removable and portable structure for the assembly of the parts of a wind turbine tower and for later rotation of the wind turbine once assembled.
Patent application WO2004101990 contemplates a mechanism with which to carry out the vertical manufacturing of the tower in the very place where the wind turbine is to be installed.
However, none of these inventions are similar to nor do they provide the advantages of the lifting device for the assembly of a wind turbine which is described below.